Stainless Steel CF20-AC (Spheroidize annealed)
Heat-treated state
ASTM CF20 · UNS J92602 · JIS SCS12
Cheapest condition for non-critical, low-corrosivity parts; interdendritic carbides raise hardness but cut ductility and intergranular corrosion resistance.
Values for the AC condition
Other CF20 tempers and conditions
CF20 is listed in 3 conditions; see the grade overview at CF20.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
STDefault Solution annealed | Standard supply condition: carbides dissolved and quenched in for maximum ductility and corrosion resistance. | 255 | 530 | 38 | 156 HB | — |
ST | Choose for cylindrical pump sleeves/liners where centrifugal soundness gives slightly higher and more consistent properties. | 270 | 560 | 40 | 160 HB | 2.4 % IACS |
ACThis page Spheroidize annealed | Cheapest condition for non-critical, low-corrosivity parts; interdendritic carbides raise hardness but cut ductility and intergranular corrosion resistance. | 275 | 520 | 22 | 175 HB | 2.4 % IACS |
What is CF20-AC?
CF20-AC is CF20 heat treated to AC — cheapest condition for non-critical, low-corrosivity parts; interdendritic carbides raise hardness but cut ductility and intergranular corrosion resistance. CF20-AC has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 77% of stainless steel grades. Elongation at break is 22% and the elastic modulus is 193 GPa (28 Msi). CF20-AC has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,400°C (2,552 °F). ST is the default condition FabDigit quotes; AC is available on request or by drawing note.
Limitations
- Limited formability — 12/100, worse than 93% of stainless steel grades
- Difficult to weld — 40/100, worse than 83% of stainless steel grades
- Needs corrosion protection — 48/100, worse than 80% of stainless steel grades
- Low fracture toughness — 80 MPa·√m (72.8 ksi·√in), worse than 79% of stainless steel grades
- Low strength — 275 MPa (39.9 ksi), worse than 77% of stainless steel grades
CF20-AC properties
Typical room-temperature values for CF20-AC; 22 are specific to this condition. Other listed values are CF20 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
CF20-AC has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
CF20-AC has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 77% of stainless steel grades. Elongation at break is 22% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
CF20-AC is rated for continuous service to 650°C (1,202 °F). It conducts heat at 16.2 W/m·K (9.36 BTU/hr·ft·°F), better than 64% of stainless steel grades. Thermal expansion is 17.2 µm/m·K (9.56 µin/in·°F).
Electrical3
CF20-AC conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (48/100), worse than 80% of stainless steel grades.
Sustainability4
Producing a kilogram of CF20-AC takes about 53 MJ of energy and emits 4.6 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 80%.
Manufacturability8
CF20-AC's machinability is poor (33/100, worse than 57% of stainless steel grades); weldability fair (40/100); formability not recommended (12/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CF20-AC
Is CF20 easy to machine?
Work-hardens rapidly — use rigid setups, sharp positive-rake carbide, heavy positive feed and flood coolant; avoid dwelling.
Can CF20 be welded?
Weldable with 308/308L filler (GTAW/SMAW), but the 0.20 %C matrix sensitizes readily; re-solution treat welded pressure parts or accept intergranular risk.
Can CF20 be formed, bent or molded?
Sand or investment casting grade with good fluidity; allow ~2.0–2.5 % shrinkage and generous risering because of the wide freezing range.
What surface finishes work on CF20?
Pickle and passivate per ASTM A967 or electropolish; shot blasting alone leaves an oxide skin that degrades corrosion performance.
CF20 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Chigh-carbon variant of CF8 | ≤ 0.2 | 0.15 |
| Mn | ≤ 1.5 | 1 |
| Si | ≤ 2 | 1.3 |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Cr | 18 – 21 | 19.5 |
| Ni | 8 – 11 | 9.5 |
| Fe | balance | — |
CF20-AC — frequently asked
What is CF20-AC used for?
CF20-AC is typically used for general purpose valve and pump castings, fittings and decorative hardware. In short: higher-carbon cast CF8; general corrosion-resistant castings; sensitizes when welded.
What is the yield strength of CF20-AC?
CF20-AC has a typical yield strength of 275 MPa (39.9 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 77% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is CF20-AC easy to machine?
Not especially — machinability is rated poor (33/100, worse than 57% of stainless steel grades). Work-hardens rapidly — use rigid setups, sharp positive-rake carbide, heavy positive feed and flood coolant; avoid dwelling.
Can CF20-AC be welded?
With care — weldability is rated fair (40/100). Weldable with 308/308L filler (GTAW/SMAW), but the 0.20 %C matrix sensitizes readily; re-solution treat welded pressure parts or accept intergranular risk.
What surface finishes work on CF20-AC?
Pickle and passivate per ASTM A967 or electropolish; shot blasting alone leaves an oxide skin that degrades corrosion performance.
Can CF20-AC be formed, bent or molded?
Sand or investment casting grade with good fluidity; allow ~2.0–2.5 % shrinkage and generous risering because of the wide freezing range.
What is the maximum service temperature of CF20-AC?
CF20-AC is rated for continuous use to about 650°C (1,202 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CF20-ST and CF20-AC?
ST is the default condition — standard supply condition: carbides dissolved and quenched in for maximum ductility and corrosion resistance. AC: cheapest condition for non-critical, low-corrosivity parts; interdendritic carbides raise hardness but cut ductility and intergranular corrosion resistance. Yield strength is 255 MPa in ST versus 275 MPa in AC.
Sources
- ASTM A743/A743M — Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application — ASTM International (2019)
- JIS G 5121 — Corrosion-resistant cast steels (SCS12) — JSA (2003)
- Steel Castings Handbook, 6th ed. — Steel Founders' Society of America / ASM (1995)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.13B — Corrosion: Materials — ASM International (2005)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.